The present invention relates to motor operator mechanisms having specific, but not necessarily limited application to industrial circuit breakers. More particularly, the present invention relates to a variable drive coupling link assembly capable of allowing the motor operator mechanism to coast to a stop while being effectively drivingly decoupled from the circuit breaker or other instrumentality.
In their application to circuit breakers, motor operator mechanisms are utilized in lieu of manual means, such as an operating handle, to charge the breaker's spring powered contact operating mechanism preparatory to contact reclosure after the breaker has been tripped open. Typically, the motion of the motor operator mechanism must be rather precisely tailored to a particular breaker's contact operating mechanism. This is particularly so with regard to the start and stop positions of the motor operator mechanism. Typically, these start and stop positions are virtually one in the same, termed a "home" position. Under these circumstances, it is eessential that the motor operator mechanism stop rather precisely in its home position at the conclusion of a charging cycle in order that it be in the proper position to start the next charging cycle. To achieve this, prior art motor operator mechanisms have utilized braking techniques, either mechanical braking, dynamic motor braking or both, which are effectuated essentially coincidentally with motor de-energization as the motor operator mechanism arrives at its home position. While these braking techniques are generally effective in abruptly stopping a motor operator mechanism within acceptable limits of its home position, they do indeed add cost and complexity to the motor operator mechanism. Moreover, any braking technique poses potential field service problems.
It is accordingly an object of the present invention to provide an improved assembly for variably drive coupling a motor operator mechanism with an operator member of an instrumentality.
A further object is to provide a variable drive coupling assembly of the above character operating to decouple the motor operator mechanism from the operator member at the conclusion of an operating cycle and thus eliminate the need for motor operator mechanism braking provisions.
Another object is to provide a variable drive coupling assembly of the above character, operating to automatically establish a lost motion coupling between the motor operator mechanism and the operator member at the conclusion of each operating cycle such that the former may be permitted to coast to a stop.
Yet another object is to provide a variable drive coupling assembly of the above character operating to automatically compensate for the effects of the lost-motion connection during each operating cycle and thus achieve uniformity of operator member movement.
A further object is to provide a variable drive coupling assembly of the above character which is efficient in design and reliable in operation.
Other objects of the invention will in part be obvious and in part appear hereinafter.